TABLE 2.
General profile and expression dynamics of placental miRNAs.
| miRNA categories |
|||||
| Category | All miRNAs | C19MCa chr19q13.42 | C14MCb chr14q32.31 | miR-371–373c chr19q13.42 | Other known or detected miRNAs |
| (A) Comparative general profile of miRNA categories | |||||
| Gene cluster size (kb) | n.a. | ∼100 kb | ∼250 kb | ∼1.1 kb | n.a. |
| Placenta-specific | n.a. | All | All | All | n.a. |
| Parent of origin expression | Most biallelic | Paternal | Maternal | Unknown | Most biallelic |
| All miRNA genesd (n) | 1,792 | 46 | 52 | 4 | 1,690 |
| All mature miRNA transcriptsd (n) | 2,656 | 67 | 94 | 8 | 2,487 |
| All identified placental mature miRNA transcripts in this study (n) | 2,652 | 67 | 93 | 8 | 2,484 |
| Placental mature miRNA transcripts with adequate expression level for confident statistical testing (n)e | 417 | 65 | 58 | 2 | 292 |
| (B) Expressional patterns from first to second trimester – from second trimester to term pregnancy (miRNA mature transcripts: n, %)e,f | |||||
| Down – Down | 30 (7.2%) | 2 (3.1%) | 8 (13.8%) | 0 (0%) | 20 (6.8%) |
| Down – No change | 67 (16.1%) | 21 (32.3%) | 1 (1.7%) | 2 (100%) | 43 (14.7%) |
| Down – Up | 28 (6.7%) | 14 (21.5%) | 0 (0%) | 0 (0%) | 14 (4.8%) |
| Up – Up | 35 (8.4%) | 0 (0%) | 0 (0%) | 0 (0%) | 35 (12.0%) |
| Up – No change | 41 (9.8%) | 0 (0%) | 7 (12.1%) | 0 (0%) | 34 (11.6%) |
| Up – Down | 26 (6.2%) | 0 (0%) | 11 (19.0%) | 0 (0%) | 15 (5.1%) |
| No change – Down | 54 (13.0%) | 2 (3.1%) | 26 (44.8%) | 0 (0%) | 26 (8.9%) |
| No change – Up | 38 (9.1%) | 4 (6.2%) | 0 (0%) | 0 (0%) | 34 (11.6%) |
| No change – No change | 98 (23.5%) | 22 (33.8%) | 5 (8.6%) | 0 (0%) | 71 (24.3%) |
aPrimate-specific miRNA cluster. bEutherian-specific miRNA cluster. cHomologous with the mouse miR-290–295 cluster (Wu et al., 2014). dData from miRBase version 22.1 (Kozomara et al., 2019). eMedian raw read counts over 50 across all analyzed samples; empirically determined transcript level for robust differential expression testing. fMajor patterns of expression dynamics are highlighted in bold; the expected proportion given an equal representation of each pattern is ∼11%. n.a., not applicable.